The engine is skipping combustion events across more than one cylinder, or in no fixed pattern. The control unit detects this from tiny variations in crankshaft speed. Unlike a single-cylinder misfire, a random one usually points at something the whole engine shares: fuel, spark, air or compression.
The engine is skipping combustion events across more than one cylinder, or in no fixed pattern. The control unit detects this from tiny variations in crankshaft speed. Unlike a single-cylinder misfire, a random one usually points at something the whole engine shares: fuel, spark, air or compression.
The code is stored by the engine control unit the moment the reading falls outside the range the manufacturer allows. Stored is not the same as diagnosed: P0300 names the symptom the car detected, not the part that caused it. That is why the repair figures below sit in a range rather than at a single price.
In rough order of how often each one turns out to be the culprit:
Parts cost roughly the same wherever you are. What moves the total is the shop rate, which is why the same job is two to three times the price in the United States that it is in Italy. These figures assume an independent workshop, not a franchised dealer, and cover the cheapest and the most expensive of the causes listed above.
| Country | Parts | Labour | Total |
|---|---|---|---|
| United States | $25 to $650 | $60 to $480 | $85 to $1150 |
| United Kingdom | £20 to £540 | £40 to £320 | £60 to £860 |
| Germany | €25 to €600 | €50 to €400 | €75 to €1000 |
| Italy | €25 to €600 | €20 to €180 | €50 to €780 |
Based on 0.5 to 4.0 hours of book labour at local shop rates, plus parts at local retail. Indicative ranges, not quotes.
No. Driving on with this fault risks further damage, so the car should be recovered rather than driven.
Usually yes, because the warning light will be on, and an illuminated engine light fails the visual part of the check in every market we cover.
Clearing the code the day before a test is a false economy: erasing the memory also resets the readiness monitors, and a car that arrives with its monitors incomplete is refused on that ground alone in most testing regimes.
Treat this one as a reason to walk away unless the seller has a recent invoice for the repair. It is expensive, it does not fix itself, and a seller who has lived with it for months has probably left other things alone too.
The thing worth checking is not the code on its own. It is whether the memory was cleared recently. Every car keeps two numbers alongside the fault list: the distance travelled since the codes were last erased, and the state of the readiness monitors. A car with no stored faults, incomplete monitors and 30 km since the last reset was wiped in the seller's driveway, probably this week. That combination tells you more than any single code does.
TrustThisCar reads all of it during the viewing, in three minutes, with the kind of Bluetooth adapter that costs about 20 euro: stored, pending and permanent codes, readiness monitors, distance since the last reset, and a verdict in plain words you can send to the seller while you are still standing next to the car.
The engine is skipping combustion events across more than one cylinder, or in no fixed pattern. The control unit detects this from tiny variations in crankshaft speed. Unlike a single-cylinder misfire, a random one usually points at something the whole engine shares: fuel, spark, air or compression.
No. Driving on with this fault risks further damage, so the car should be recovered rather than driven.
Usually yes, because the warning light will be on, and an illuminated engine light fails the visual part of the check in every market we cover.
It depends on the shop rate where you live: United States $85 to $1150, United Kingdom £60 to £860, Germany €75 to €1000, Italy €50 to €780. Parts are close to the same everywhere; labour is what moves the total.
Last reviewed 2026-10-03.